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杭州市肛肠医院看脱肛多少钱飞排名云管家浙江省妇幼保健院看内痔多少钱

2017年12月12日 12:20:40来源:飞度咨询医院排行榜

  • Science and technology科学技术Solar physics太阳物理学Sun down落山的太阳Several lines of evidence suggest that the sun is about to go quiet据的一些方式表明太阳即将变平静spots of bother?太阳黑子的困扰?DURING the four centuries that it has been studied in detail, the sun has usually behaved in a regular manner.太阳已被详细研究了四百年,它通常以规则的方式反应。The number of spots on its surface has waxed and waned in cycles that last, on average, 11 years.太阳表面的黑子数在其一般延续11年的活动周期内增增减减。Such cycles begin with spots appearing in mid-solar latitudes and end with them near the equator.这样的周期活动以太阳黑子在其中纬度出现开始并随着黑子移动到赤道附近而终结。And the more spots there are, the more solar storms there are around.而且太阳黑子的数目越多,周围就会有越多的太阳风暴。Sometimes, though, the sun sulks and this solar cycle stops.然而,太阳有时也会生气,之后这种太阳活动周期就停止了。That has happened twice since records began:自从对这种太阳活动周期有记载以来,这种现象已经发生了两次了:during the so-called Maunder minimum of 1645 to 1715 and the Dalton minimum of 1790 to 1830.就是所称的1645年至1715年蒙德极小期和1790年至1830年道尔顿极小期期间。These coincided with periods when global temperatures were lower than average, though why is a matter of debate.这些现象与全球气温低于平均水平时相一致,虽然这是为什么争议的一个问题。An absence of sunspots also means an absence of solar flares and their more violent siblings, coronal mass ejections.缺少太阳黑子也意味着太阳耀斑以及它们更强烈的同胞-日冕物质抛射的不存在。Such outbursts disrupt radio and satellite communications, electricity grids and a variety of electronic equipment, so the pattern of solar activity is of more than academic interest.这种大爆发会干扰无线电和卫星通信,电网和各种电子设备,因此太阳活动方式超越了学术兴趣。A new solar minimum, then, would test theories about how the climate works and also make communications more reliable.然而,一个新的太阳极小期将会测试关于气候如何起作用的理论以及还将使得通信更加可靠。And many solar physicists think such a new minimum is on the cards.而且许多太阳物理学家认为这样一个新的太阳极小期很可能发生。A group of them, who all work for Americas National Solar Observatory, have just had a meeting in New Mexico, under the aegis of the American Astronomical Society, to announce their latest results.在美国天文学会的主持下,美国国家太阳天文台工作的一群太阳物理学家刚刚在新墨西哥州举行了一次会议来宣布他们的最新成果。Frank Hill and his team were the discoverers, 15 years ago, of an east-west jet stream in the sun.弗兰克·希尔和他的研究小组就是15年前太阳内东西高速气流的发现人员。They also worked out that the latitude of this wind is related to the sunspot cycle.他们还计算出这次太阳风的纬度和太阳黑子的活动周期相关。At the beginning of a cycle the jet stream is found, like sunspots, in mid-latitudes.在一个活动周期开始的时候,就可以找到高速气流,像中纬度地区的太阳黑子。As the cycle progresses, it follows the spots towards the equator.随着活动周期的进展,高速气流随着太阳黑子向太阳的赤道方向移动。Intriguingly, however, Dr Hills studies indicate that the jet stream of a new cycle starts to form years before the sunspot pattern.然而,让人感兴趣的事情是,希尔士的研究表明一个新太阳活动周期的高速气流在太阳黑子活动方式前开始形成。This time, that has not happened.这次,高速气流还未产生。History suggests a new cycle should begin in 2019.历史表明一个新太阳活动周期应该开始于2019年。If the sun were behaving itself, Dr Hills team would have seen signs of a new jet stream in 2008 or .假如太阳自我反应的话,希尔士研究人员在2008年或年早已观察到新高速气流的迹象了。They did not.但是他们没有看到这些情况。Nor are there indications of one even now.即使现在,也没有一个迹象出现。If a change in the jet stream really is a leading indicator of solar activity, then no new cycle is on the horizon.如果高速气流的变化真地是太阳活动最重要的指示物,那么新的太阳活动周期还未露端倪。The second study which suggests something odd is happening looked at the strengths of sunspots.表明奇怪的事情正在发生的第二项研究检查了太阳黑子的活力。Matthew Penn and William Livingston have analysed 13 years of data which indicate that, independently of the number of spots around, there has been a decrease in their strength.马修·佩恩威廉·利文斯敦已独立见解地分析了大致太阳黑子数的13年的数据表明这些黑子的活力已经下降了。Sunspots are caused by irruptions into its surface of the suns deeper magnetism.太阳黑子是由入侵活动进入太阳深层磁性表面造成的。These create local drops in temperature, which make the surface gas darker.这些入侵活动导致了局部气温下降,使得太阳表面气体颜色更深。Over the period which Dr Penn and Dr Livingston analysed, the average magnetic strength of the irruptions has declined.佩恩和利文斯顿士分析表明,入侵活动的平均磁场强度已有所下降。Below a certain threshold, they will not be strong enough to overcome the convective mixing of the gas at the surface, and spots will disappear altogether.低于一定的临界值的话,它们将不足以克表面气体的对流混合,因而太阳黑子将完全消失。If the present trend continues, that will happen in 2021.如果目前的趋势继续下去,那么2021年太阳黑子就会消失。The third measure of the suns decline is in its outer atmosphere, the corona.太阳衰落的标准就是其外层的气体日冕。At each solar maximum, the corona sloughs off the magnetic fingerprint of the previous cycle by pushing it to the poles.在每次太阳极大期,日冕通过把气体推向两极而使前一活动周期的磁性特征消退掉。According to Richard Altrock, the leader of another NSO team at the meeting, that does not appear to be happening in the present cycle.根据会议上美国国家太阳天文台的另一研究组的领导理查德·阿尔乔克所说,目前的太阳活动周期那种现象没有出现。It looks, then, as if a new, extended solar minimum is about to begin.然而,看上去好像一个新延续的太阳极小期将要开始。That is good news for operators of communications satellites.对通信卫星的经营者来说,这是好消息。And it is interesting news for those who worry about global warming.而且这对那些担心全球气温变暖的那些人来说是个令人有趣的新闻。If the Maunder and Dalton minima actually did affect the climate,如果蒙德和道尔顿极小期确实影响了气候,then a new one might counteract the effects of the extra greenhouse gases people are now pumping into the atmosphere—at least, until the solar cycle returns.那么新的太阳活动极小期可能抵消人们现在大量释放到空气中额外温室气体的影响-至少要到太阳活动周期恢复时。Whether the breathing space thus granted would be used wisely or squandered is another matter.无论是如此承认的呼吸空间会被明智地使用还是被大手大脚地挥霍掉将是另一回事。Do not expect that debate to be as placid as the spotless sun.不要指望辩论就像一尘不染的太阳那么宁静安详。 /201308/251230。
  • Science and technology科学技术Bespoke pets定制宠物Just press print只需按一下打印键It will soon be possible to design and build household animals to order按需定制宠物很快将成为现实I could have sworn I ordered this in blue我确定我当初定的是一只蓝色的ONE of the most interesting technological trends of the past few years has been the rise of additive manufacturing. 直接数字化制造算得上是过去几年当中兴起的最新奇的新兴科技之一。This technique, which uses three-dimensional printing to make objects ranging from violins to pilotless aircraft, 这一技术是使用三维打印技术制造从小提琴到无人机等各种产品。allows the construction of individual objects at the whim of the designer. 通过这种技术,设计者可以根据自己天马行空的想象来制造单件产品。Now, a small Californian company, the Gene Duplication Corporation, based in San Melito, proposes to push the technology to its limits. 如今,一家总部位于加州圣美利托镇的小公司—基因复制公司打算将这一技术运用到极致。On Sunday it will announce plans to use 3D printing to make bespoke pets.本周日,该公司将宣布他们计划采用三维打印技术为顾客定制宠物。GeneDupe, as the firm is known colloquially, has previously focused on the genetic engineering of animals. 该公司通常被人们称为GeneDupe,之前一直致力于动物基因工程的研究。However Paolo Fril, the companys boss, is keen to expand into manufacturing them from scratch. 不过,公司的老板保罗-弗里热切地希望能够扩展业务范围:从零开始将动物制造出来。PrintaPet does just that.就是要实现这个目标。The idea of printing organs such as kidneys for transplant has been around for several years. 打印用于移植的器官的想法在几年前久就已经出现。It works by growing separate cultures of individual cell types, and then spraying them out, 通过将不同种类的单个细胞分开培养,layer by layer, in combination with a binding agent called a hydrogel, to build up the correct shape.然后将它们一层一层喷洒出来,加上一种称作水凝胶的粘合剂,就可以构建出想要的形状。Printing an organ this way is fairly easy. 通过这种方式打印一个器官相当简单。A kidney, for instance, has only eight cell types. 比如,打印一个肾脏只需要用到八种不同类型的细胞。An entire mammalian body, though, has 220 cell types. 不过,一个完整的哺乳动物机体中有220种不同类型的细胞。Laying these down in the correct order is a much more complex problem. 按照正确的顺序将这些细胞组合起则要复杂得多。To solve it, GeneDupes researchers used nanotomography, a precise form of CT scanning that has a resolution of 500 nanometres, 为了解决这个问题,GeneDupe的研究人员运用纳米断层摄影技术对不同动物中每一个细胞的位置与特性进行分析。to analyse the position and nature of every single cell in a variety of animals, particularly breeds of dog. 纳米断层摄影技术是一种更为精密的计算机断层扫描技术,其分辨率可达500纳米。This knowledge not only permits existing breeds to be re-created, 获得动物机体中细胞的位置与特性信息以后,不仅可以将现有品种再制造出来,but allows entirely new combinations of form, colour and behaviour to be invented, at the customers command.还可以根据顾客的需求,将动物的形状、颜色及习性进行组合制造出一些全新的品种。GeneDupes Universal Pet Printer is loaded with each of the 220 cell types, and is programmed with a three-dimensional map of the creature it is to create. 公司GeneDupe的万能宠物打印机内已经加载了构成哺乳动物机体的所有220种细胞,并且根据将要打印的动物体中细胞的三维信息图谱编写了打印程序。That is devised by the firms scientists, based on what the nanotomographic analysis has told them about the results of arranging cells in different ways in an animals body.根据纳米断层扫描分析的结果,该公司的科学家可以得知以不同的方式对动物体内的细胞进行组合的结果。这也是打印程序的编写依据。The cells themselves are stored in suspension, in glass reservoirs, and each reservoir is connected to a computer-controlled spray gun. 用于打印的细胞储存在装满悬浮液的玻璃容器中,每个容器都与一根电脑控制的喷相连。The hydrogels are stored separately. 水凝剂分开储存。One, known as osteogel, is particularly important, as this solidifies to provide the animals initial skeleton. 一种称为osteogel的水凝剂相当关键,它固化以后形成了动物最初的骨架。Once the new creature is up and running,the various hydrogels are gradually replaced by natural secretions. 一旦这种新制造出来的动物的机体能够正常工作以后,各种水凝剂将逐渐被自然分泌物所取代。In the case of osteogel, that secretion is bone.取代osteogel的就是骨骼。The biggest difficulty Dr Fril has encountered is with nerve cells. 弗里士遇到的最棘手的问题是如何处理神经细胞。Unlike most other types of cell, which are small, the protuberances from a nerve cell, known as axons and dendrites, may stretch from the animals spinal cord to the tips of its toes. 和其他大多数种类体积较小的细胞不同,神经细胞上的突起可能从脊髓一直延伸到脚趾尖。To deal with this problem, the pet printer leaves a hole in each layer of cells at every point through which a nerve cell is supposed to pass. 为了解决这个问题,宠物打印机在每个细胞层都留有一个小孔,以便神经细胞的突起能从中穿过。The holes are then filled with nerve-growth factor before the next layer is printed, 之后,在打印下一个细胞层之前往这些小孔中注满神经生长因子。so that when the main body of the nerve cell is sprayed into place it rapidly grows axonal and dendritic protuberances to the right destinations.这样神经细胞的主体喷洒到位之后便迅速长出树突与轴突并延伸到特定的末端。Knowing how to print nerve cells, is, in fact, the key to the whole thing.事实上,打印神经细胞是整个工作的关键。Size apart, a healthy heart, kidney or liver is pretty much the same in a retriever or a Rottweiler. 除了尺寸不同之外,要给拾物犬与罗威纳犬制造一颗健康的心脏、一个肾脏或者肝脏的步骤都差不多。Coat colour, an important consideration for many owners, is easily dealt with by picking the right pattern of melanocyte cells in the skin. 许多宠物的主人都比较在意动物皮毛的颜色,要打印出不同的颜色只需要在皮肤中选取合适的黑色素细胞排列形式就能轻松实现。But an animals temperament is a very different matter.但要构造动物的脾性却比这要复杂得多。Controlling temperament means laying down the right mixture of nerve cells in the brain, since different types of cell have different effects on personality. 要控制动物的脾性需要正确构造动物大脑中的神经细胞组合,因为不同的神经细胞对动物脾性有不同的影响。Having worked out how to do this, GeneDupe is able to offer pets that have had their behavioural characteristics fine-tuned. GeneDupe公司已经攻克了这个难题,现在他们可以对定制宠物的行为习性进行细微的调整。If you want a docile Rottweiler, or even an aggressive retriever, you can have one made to your exact specifications. 如果你想要一只性情温顺的罗威纳犬,或者是一只凶猛的拾物犬,你都可以给出详细的要求然后定做一个。Dr Fril, though, thinks that the most popular modification will be his tweaking of canine scent-marking behaviour so that local lampposts are no longer the preferred sites of relief and communication. 不过,弗里士认为他们对犬类气味标记行为的修改可能最受顾客青睐,因为经过修改之后的宠物不会再把路灯当成方便及与同类沟通的场所。Instead, GeneDupes pooches are pre-wired to recognise the companys proprietary DoggieLoos, which have a distinctive odour that is perceptible to canids, but not humans.GeneDupe对其制造的都预先进行了处理,它们能够识别该公司的厕所。这种厕所能够散发出一种人类无法察觉但是犬类却能够识别的特殊气味。There are still a few technical difficulties to overcome, of course, but Dr Fril plans to start taking orders soon. 当然,离最终实现还有一些技术难题需要攻克,但是弗里士计划不久就开始接受订单。And he is aly looking forward to the firms next product, custom-printed boyfriends and girlfriends for those who cannot find the right partner by conventional means,而他现在已经迫不及待地想开发公司的下一代产品—定制恋人。这款产品主要是针对那些通过传统方式没能找到合适伴侣的人,a surprisingly large proportion of the population. 这个群体占人口总数的比例远远超出了人们的想象。If all goes well, these will be available by St Valentines day. 如果一切顺利,这款产品在情人节之前就会上市。If not, customers will probably have to wait until April 1st of next year.不然的话,消费者可能就得等到明年的愚人节了。 /201307/247555。
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